Coeliac disease: beyond genetic susceptibility and gluten. A narrative review

Predictive factors for the diagnosis of coeliac disease in children and young people in primary care: A systematic review and meta-analysis

BACKGROUND

Coeliac Disease (CD) often has its onset in childhood and affects 1% of the population. This review aimed to identify important predictive factors for coeliac disease in children and young people which could help GPs decide when to offer testing.

METHODS

We searched MEDLINE, Embase and Cochrane Library to April 2024. Included studies were observational or randomized trials reporting the risk of CD when exposed to predictive factor(s) in people ≤25 years of age. Genetic factors were excluded. Risk of Bias was assessed using the Newcastle-Ottawa Scale. Random effects meta-analysis was performed for factors reported in ≥5 studies to calculate pooled odds ratios (OR) or standardized mean differences (SMD).

RESULTS

Of 11,623 unique abstracts, 183 were included reporting on 140+ potentially associated factors. Meta-analyses of 28 factors found 14 significant associations with CD diagnosis: having type 1 diabetes (OR 8.70), having a first degree relative with coeliac disease (OR 5.19), being of white ethnicity (OR 2.56), having thyroid disease (OR 2.16), being female (OR 1.53), more frequent gastroenteritis in early childhood (OR 1.48), having frequent respiratory infections in early childhood (OR 1.47), more gluten ingestion in early life (OR 1.25), having more infections in early life (OR 1.22), antibiotic use in early childhood (OR 1.21), being born in the summer (OR 1.09), breastfeeding (OR 0.79) older age at diagnosis of type 1 diabetes (OR 0.64), and heavier weight (SMD -0.21). The final three were associated with lower risk of CD diagnosis.

DISCUSSION

This is the first systematic review and meta-analysis of predictive factors for CD in children. Amongst the 14 factors we identified that were significant, three were potentially modifiable: breast feeding, antibiotic use and amount of gluten ingestion in early childhood. This work could inform the development of clinical support tools to facilitate the early diagnosis of CD.

How the Microbiota May Affect Celiac Disease and What We Can Do

Celiac disease (CeD) is an autoimmune disease with a strong association with human leukocyte antigen (HLA), characterized by the production of specific autoantibodies and immune-mediated enterocyte killing. CeD is a unique autoimmune condition, as it is the only one in which the environmental trigger is known: gluten, a storage protein present in wheat, barley, and rye. How and when the loss of tolerance of the intestinal mucosa to gluten occurs is still unknown. This event, through the activation of adaptive immune responses, enhances epithelial cell death, increases the permeability of the epithelial barrier, and induces secretion of pro-inflammatory cytokines, resulting in the transition from genetic predisposition to the actual onset of the disease. While the role of gastrointestinal infections as a possible trigger has been considered on the basis of a possible mechanism of antigen mimicry, a more likely alternative mechanism appears to involve a complex disruption of the gastrointestinal microbiota ecosystem triggered by infections, rather than the specific effect of a single pathogen on intestinal mucosal homeostasis. Several lines of evidence show the existence of intestinal dysbiosis that precedes the onset of CeD in genetically at-risk subjects, characterized by the loss of protective bacterial elements that both epigenetically and functionally can influence the response of the intestinal epithelium leading to the loss of gluten tolerance. We have conducted a literature review in order to summarize the current knowledge about the complex and in part still unraveled dysbiosis that precedes and accompanies CeD and present some exciting new data on how this dysbiosis might be prevented and/or counteracted. The literature search was conducted on PubMed.gov in the time frame 2010 to March 2024 utilizing the terms "celiac disease and microbiota", "celiac disease and microbiome", and "celiac disease and probiotics" and restricting the search to the following article types: Clinical Trials, Meta-Analysis, Review, and Systematic Review. A total of 364 papers were identified and reviewed. The main conclusions of this review can be outlined as follows: (1) quantitative and qualitative changes in gut microbiota have been clearly documented in CeD patients; (2) intestinal microbiota's extensive and variable interactions with enterocytes, viral and bacterial pathogens and even gluten combine to impact the inflammatory immune response to gluten and the loss of gluten tolerance, ultimately affecting the pathogenesis, progression, and clinical expression of CeD; (3) gluten-free diet fails to restore the eubiosis of the digestive tract in CeD patients, and also negatively affects microbial homeostasis; (4) new tools allowing targeted microbiota therapy, such as the use of probiotics (a good example being precision probiotics like the novel strain of B. vulgatus (20220303-A2) begin to show exciting potential applications.

Why are western diet and western lifestyle pro-inflammatory risk factors of celiac disease?

The prevalence of celiac disease increased in recent years. In addition to the genetic and immunological factors, it appears that environmental determinants are also involved in the pathophysiology of celiac disease. Gastrointestinal infections impact the development of celiac disease. Current research does not directly confirm the protective effect of natural childbirth and breastfeeding on celiac disease. However, it seems that in genetically predisposed children, the amount of gluten introduced into the diet may have an impact on celiac disease development. Also western lifestyle, including western dietary patterns high in fat, sugar, and gliadin, potentially may increase the risk of celiac disease due to changes in intestinal microbiota, intestinal permeability, or mucosal inflammation. Further research is needed to expand the knowledge of the relationship between environmental factors and the development of celiac disease to define evidence-based preventive interventions against the development of celiac disease. The manuscript summarizes current knowledge on factors predisposing to the development of celiac disease including factors associated with the western lifestyle.

Autoimmune Thyroid Disorders Are More Prevalent in Patients with Celiac Disease: A Retrospective Case-Control Study

Background. Among patients with celiac disease (CD), there is an increased incidence of autoimmune thyroid disorders (AITDs), with hypothyroidism being more frequent than hyperthyroidism. This retrospective case-control study aimed to explore the prevalence of TDs in a population of adult celiac patients from Northern Sardinia, a geographic area with a high prevalence of autoimmune disorders. Methods. Data were collected from consecutive patients with CD (cases) and without CD (controls) who were undergoing upper endoscopy and referred to a tertiary gastroenterology section of a teaching hospital (University of Sassari, Italy). Thyroid disorders were stratified as (i) autoimmune: including Hashimoto’s disease in euthyroidism or with hypofunction, and Graves’ disease; or (ii) non-autoimmune: thyroid nodules/goiter, iatrogenic thyroid hypo/hyperfunction, and thyroidectomy for any reason, including cancer. Results. Among a total of 8489 participants (females 5839, 64.7%) enrolled, there were 623 (7.3%) celiac patients and 7866 controls (92.7%). The overall frequency of TDs was 1177 (13.9%) and was higher (26.0%) in celiac patients than in controls (12.9%) (p < 0.001). The difference between AITDs (15.4% vs. 7.5%) and no-AITDs (2.7% vs. 1.1%) was statistically significant in CD patients compared with controls, respectively, and prevailed in the fifth and sixth decades. Hashimoto’s thyroiditis was more commonly associated with gland hypofunction. Odds ratios with their 95% confidence intervals (CIs) for the presence of AITDs were calculated, adjusting for sex, age, body mass index, smoking habits, occupation, and residence, and they were 2.387 (95% CI 1.857−3.068, p < 0.001) in CD patients, 5.855 (95% CI 4.434−7.731, p < 0.001) for female sex, and 1.012 (95% CI, 1.007−1.017, p < 0.001) for age. Conclusion. These results suggest the need for surveillance for TDs in patients with CD at onset and during follow-up.

Efficacy of Jianpiyangxue granule on gastrointestinal autonomic nerve dysfunction and its impact on adverse reactions

OBJECTIVE

To explore the efficacy of Jianpiyangxue granules on gastrointestinal autonomic nerve dysfunction and their impact on adverse reactions.

METHODS

From September 2016 to September 2020, 120 patients with gastrointestinal autonomic nerve dysfunction treated in our hospital were retrospectively selected and randomly assigned to a treatment group (TG) which was administered Jianpiyangxue granules prepared by our hospital and a control group (CG) which was administered routine Western medicine treatment (B vitamins + oryzanol). There were 60 patients in each group. The clinical efficacy and incidences of adverse effects were compared between the groups. The gastrointestinal hormone indexes, the inflammatory cytokines, and the immune indexes were analyzed before and after the therapy. The gastrin (GAS) and motilin (MTL) levels were measured using the motilin stimulating method, and the somatostatin (SS) levels were measured using ELISA for comparison. The autonomic nerve dysfunction symptoms were used for the evaluation. The degree of neurological functional defects scale (NIHSS) was used to assess the neurological functional defect levels. The self-rating anxiety scale (SAS) and self-rating depression scale (SDS) scores were used to assess the patients' psychological statuses.

RESULTS

After the therapy, the GAS, MTL, and SS expressions in the TG were remarkably higher than they were in the CG. The CRP and IL-6 expressions in the TG were significantly lower than they were in the CG. The TG had higher IgG, IgM, and IgA levels as compared with the CG, higher grade 0 and grade 1 scores on the gastrointestinal autonomic nerve dysfunction, but lower grade 2 and 3 scores were observed compared to the CG. Significantly lower NIHSS, SAS, and SDS scores were recorded in the TG compared with the CG. The TG yielded more promising outcomes in terms of the total effective rate and the incidences of adverse reactions than the CG.

CONCLUSION

Jianpiyangxue granules contribute to enhancing the clinical efficacy, reducing the incidence of adverse reactions, and improving the gastrin, somatostatin, and other indicators in treating gastrointestinal autonomic nerve dysfunction.

The gut microbiota and gut disease

The gut microbiota has a key role in the maintenance of good health, and in the pathogenesis of gastrointestinal diseases. These conditions include the inflammatory bowel diseases, colorectal cancer, coeliac disease and metabolic liver disease. Although the nature of the microbial disturbance in these conditions has not been fully characterised, this has not prevented the development of microbially based therapies. Microbial-changing therapies may address newly recognised pathophysiological contributors of disease and have the potential to replace or supplement standard therapies. Antibiotics play a role in initial Clostridiodes difficile disease and some specific inflammatory disorders. Probiotics have a more limited proven role. Faecal microbiota transplantation is of proven therapeutic benefit in recurrent C. difficile disease and ulcerative colitis. We review the current literature for microbiota-targeted therapies in gut disorders.

The Two Faces of Wheat

Wheat-based foods have been staple foods since about 10,000 years and constitute a major source of energy, dietary fiber, and micronutrients for the world population. The role of wheat in our diet, however, has recently been scrutinized by pseudoscientific books and media reports promoting the overall impression that wheat consumption makes people sick, stupid, fat, and addicted. Consequently, numerous consumers in Western countries have started to question their dietary habits related to wheat consumption and voluntarily decided to adopt a wheat-free diet without a medical diagnosis of any wheat-related disorder (WRD), such as celiac disease, wheat allergy, or non-celiac gluten sensitivity. The aim of this review is to achieve an objective judgment of the positive aspects of wheat consumption as well as adverse effects for individuals suffering from WRDs. The first part presents wheat constituents and their positive nutritional value, in particular, the consumption of products from whole-grain flours. The second part is focused on WRDs that affect predisposed individuals and can be treated with a gluten-free or -reduced diet. Based on all available scientific knowledge, wheat consumption is safe and healthy for the vast majority of people. There is no scientific evidence to support that the general population would benefit from a wheat-free diet.

Fecal Microbiota Signatures in Celiac Disease Patients With Poly-Autoimmunity

To date, reliable tests enabling the identification of celiac disease (CD) patients at a greater risk of developing poly-autoimmune diseases are not yet available. We therefore aimed to identify non-invasive microbial biomarkers, useful to implement diagnosis of poly-autoimmunity. Twenty CD patients with poly-autoimmunity (cases) and 30 matched subjects affected exclusively by CD (controls) were selected. All patients followed a varied gluten-free diet for at least 1 year. Fecal microbiota composition was characterized using bacterial 16S ribosomal RNA gene sequencing. Significant differences in gut microbiota composition between CD patients with and without poly-autoimmune disease were found using the edgeR algorithm. Spearman correlations between gut microbiota and clinical, demographic, and anthropometric data were also examined. A significant reduction of Bacteroides, Ruminococcus, and Veillonella abundances was found in CD patients with poly-autoimmunity compared to the controls. Bifidobacterium was specifically reduced in CD patients with Hashimoto's thyroiditis and its abundance correlated negatively with abdominal circumference values in patients affected exclusively by CD. In addition, the duration of CD correlated with the abundance of Firmicutes (negatively) and Odoribacter (positively), whereas the abundance of Desulfovibrionaceae correlated positively with the duration of poly-autoimmunity. This study provides supportive evidence that specific variations of gut microbial taxa occur in CD patients with poly-autoimmune diseases. These findings open the way to future validation studies on larger cohorts, which might in turn lead to promising diagnostic applications.